iomap: constrain the file range passed to iomap_file_unshare

File contents can only be shared (i.e. reflinked) below EOF, so it makes
no sense to try to unshare ranges beyond EOF.  Constrain the file range
parameters here so that we don't have to do that in the callers.

Fixes: 5f4e5752a8a3 ("fs: add iomap_file_dirty")
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Link: https://lore.kernel.org/r/20241002150213.GC21853@frogsfrogsfrogs
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>

diff --git a/fs/dax.c b/fs/dax.c
index becb4a6920c6aa1fc0aadb909abefbd8dddd866f..c62acd2812f8d4981aaba82acfeaf972f555362a 100644 (file)
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -1305,11 +1305,15 @@ int dax_file_unshare(struct inode *inode, loff_t pos, loff_t len,
        struct iomap_iter iter = {
                .inode          = inode,
                .pos            = pos,
-               .len            = len,
                .flags          = IOMAP_WRITE | IOMAP_UNSHARE | IOMAP_DAX,
        };
+       loff_t size = i_size_read(inode);
        int ret;
 
+       if (pos < 0 || pos >= size)
+               return 0;
+
+       iter.len = min(len, size - pos);
        while ((ret = iomap_iter(&iter, ops)) > 0)
                iter.processed = dax_unshare_iter(&iter);
        return ret;

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index c1c559e0cc07cf3d03c3871180af376180b99f69..78ebd265f42594e6c0163714d18bc4434098ae92 100644 (file)
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -1375,11 +1375,15 @@ iomap_file_unshare(struct inode *inode, loff_t pos, loff_t len,
        struct iomap_iter iter = {
                .inode          = inode,
                .pos            = pos,
-               .len            = len,
                .flags          = IOMAP_WRITE | IOMAP_UNSHARE,
        };
+       loff_t size = i_size_read(inode);
        int ret;
 
+       if (pos < 0 || pos >= size)
+               return 0;
+
+       iter.len = min(len, size - pos);
        while ((ret = iomap_iter(&iter, ops)) > 0)
                iter.processed = iomap_unshare_iter(&iter);
        return ret;